Project Summary There are now approximately 450,000 youth with autism spectrum disorder (ASD) between the ages of 16-24 in the U.S., and 50,000 more turning 18 each year. The field is bracing for a surge in demand for services. Underage alcohol use is a priority public health problem and too little is known about underage alcohol use by youth with ASD. ASD may be protective against alcohol use in individuals with intellectual disability, but 44% of youth with ASD have average or high IQ, and some evidence suggests that these ASD youth may be at increased risk for alcohol use disorder as compared to neurotypical counterparts. Information about underage alcohol use in youth with ASD, and ultimately effective prevention strategies, are needed. The proposed research will achieve two specific aims. Aim 1 is to explore, using qualitative methods, underage alcohol use and non-use by youth with ASD and without ID, ages 16-20 years old. Half of these youth will have used alcohol in the past six months and half will not (N=40). A targeted enrollment scheme will ensure that research participants include males and females. Aim 1 interviews will explore topics that include motivations to use alcohol or abstain, alcohol expectancies, refusal self-efficacy, parental communication about alcohol, peer use norms, alcohol rule-following, and perception of risks; and in those with recent alcohol use, types of alcohol consumed, how procured, where it occurred, when, with whom and in what context, perceived effects, and consequences. Aim 1 interview participants will also give feedback on a draft survey, comprising multiple measures of alcohol-related constructs, in order to improve its face validity prior to implementation in Aim 2. Aim 2 will use the refined survey to quantitatively investigate underage alcohol use in a sample of ASD vs. demographically-matched neurotypical comparison subjects (N=190). Half will have used alcohol in the past six months, and half will have abstained. Psychometrics will be assessed including factor structure and internal reliability of scales. Next, structural equation techniques will be used to evaluate relationships of alcohol- related variables with alcohol use among neurotypical vs. ASD youth in order to test hypotheses and inform theory development. In addition to assessing relationships between variables. For Aim 2, a targeted enrollment scheme to ensure that research participants include males and females will also be used. Overall, a strength of the project is its Advisory Board, comprising youth with ASD, parents of youth with ASD, and service providers. For recruitment of participants with ASD, the research team will partner with a leading national non-profit that serves the population formerly referred to as having Asperger?s, or referred to as high functioning ASD, and the Boston Medical Center Autism Program. In the long-term, the ultimate goal of this line of research is generalizable knowledge about underage alcohol use in U.S. youth with ASD and the development of evidence-based interventions to prevent it.